Enclosed spaces in the Northern climates, especially, need protection against heat loss during cold weather if they are to remain habitable, and to prevent freeze damage to their contents. Also, too high temperatures can cause damage and discomfort. Protection can be accomplished by using windows and double glazing, storm doors, heat shields, and the like, but this is expensive. Since screens usually are used in the summer, it would be beneficial to adapt them to use in the winter to prevent frost and freeze damage, and to increase their efficiency as insulators in hot weather. It would also be advantageous to provide a way of providing protection against temperature extremes which could be modified, e.g., to screen out insects, or to provide some degree of sun-shading yet permit the passage of summer breezes and the like, if desirable.
A system to protect enclosures against temperature extremes has not been discovered which eliminates the need to use continuous sheets or panes and which cuts down substantially the need for interior heaters and coolers. In essence, a water-removable film with heat loss retarding capability is applied to a screen-like cover placed over openings in the enclosure. The film bridges over the normally present smaller openings in the cover to keep out the above- and beloww-normal temperatures, e.g., by preventing or retarding heat and cold air loss. It is a feature of the discovery to permit the film to be washed off with water after danger of hot and/or cold weather has passed, restoring the openings in the cover. The invention can also be used in conjunction with single pane windows, for example, to provide a dead air space between the cover and the windows, to substantially reduce the loss of cold air or of heat to the outside.